A disk drive is a data storage device that stores data in concentric tracks on a recording media disk. During operation, the disk is rotated about an axis by a spindle motor while a transducer (head) reads/writes data from/to a target track of the disk. The magnetic recording media utilized in particular recording media disks has begun to incorporate new media technologies, such as new materials for perpendicular magnetic recording layers, in an effort to increase storage density. Many of these new media technologies entail sputtering processes performed at higher temperatures than in previous technologies. As such, the media disk at certain points during manufacture will need to be cooled down from the higher deposition temperature to a subsequent temperature more conducive to further processing, such as the formation of a carbon overcoat (COC) via a chemical vapor deposition (CVD) process.
FIG. 1A illustrates an isometric view of a conventional cooling system 100 employed within a cooling chamber of an exemplary deposition system utilized in the manufacture of magnetic media disks. As shown, the cooling system 100 includes a first cooling plate 105 positioned with a major surface opposing that of a second cooling plate 106. An external surface of each of the first and second cooling plates 105, 106 is coupled to a cooling coil 115 which forms part of a coolant loop through which a coolant may pass to chill the cooling plates 105, 106. The first and second cooling plates 105, 106 are further coupled together at an edge by a spacer 110 to form a gap between the cooling plates 105,106 through which a disk carrier 55 holding one or more media disks 50 may be disposed or passed through during a production operation. While the disk carrier 55 is disposed between opposing internal surfaces of the cooling plate 105 and 106, a coolant gas 120 is introduced through an input port 118 disposed in the spacer.
FIG. 1B illustrates a cross-sectional view of the cooling system 100 along the x-axis of the isometric view illustrated in FIG. 1A. The arrows illustrate the general direction of the coolant gas 120. As shown in FIG. 1B, after being introduced at the input port 118, the coolant gas 120 passes through the spacer 110 and flows on either side of the carrier 55 in a direction substantially parallel to both the front and back sides of the media disks 50 and the opposing surfaces of the cooling plates 105, 106. The coolant gas 120 then exits out an output (pump) port disposed at an edge (not depicted) opposite the spacer 110 to be pumped out by a pump stack (e.g., a turbomolecular pump backed by a roughing pump). Stated another way, there is a pressure drop along the y-dimension in FIG. 1 such that the coolant gas pressure at the edge of the media disk 50 proximate to the input port 118 is higher than at the edge of the media disk 50 distal from the input port 118 or proximate to a pump port.
Because a media deposition system is operated under vacuum, the cooling chamber typically operates at a nominal pressure of approximately 1 Torr. As such, cooling of the media disk 50 is dependent on heat transfer between the media disk 50 and the cooling plates 105, 106 across the spacing through which the coolant gas 120 passes. Because this heat transfer is sensitive to the coolant gas pressure, both nominal cooling rate and cooling rate uniformity are limited in the cooling system 100. For existing deposition systems to adopt the new manufacturing technologies requiring higher disk temperatures without incurring a significant reduction in disk throughput, it is advantageous to improve the cooling efficiency of cooling chambers within the deposition system.